1. Field of the Invention
The present invention relates to audio signal processing and, more specifically but not exclusively, to echo cancellation techniques.
2. Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the invention. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is prior art or what is not prior art.
As more and more products tend towards smaller and smaller size, and as hands-free communication applications grow, it has become common for product designers to place the acoustic transducers in very close proximity to each other. Having the microphones and loudspeakers in close proximity results in high acoustic coupling that can severely compromise the duplex quality of a full-duplex audio communication channel. The main reason for this compromise is related to the large acoustic-level difference between the nearby loudspeaker(s) signal and the desired local acoustic signal (talker) at the microphone(s). A larger disparity in these two acoustic levels can lead to poor double-talk detection, reduced duplexness in the audio communication channel, and a susceptibility to audible artifacts caused by loudspeaker distortion. Acoustic echo cancellers are typically based on the assumption that the acoustic coupling path is linear. Thus, loudspeaker distortion cannot be cancelled by a linear echo canceller, resulting in poor duplex performance.